/**
 * Copyright (C) 2002-2015   The FreeCol Team
 * <p>
 * This file is part of FreeCol.
 * <p>
 * FreeCol is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 * <p>
 * FreeCol is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * <p>
 * You should have received a copy of the GNU General Public License
 * along with FreeCol.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.sf.freecol.client.gui;

import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.util.logging.Logger;

import net.sf.freecol.client.FreeColClient;
import net.sf.freecol.common.model.PathNode;
import net.sf.freecol.common.model.Tile;
import net.sf.freecol.common.model.Unit;


/**
 * Listens to the mouse being moved at the level of the Canvas.
 */
public final class CanvasMouseMotionListener extends AbstractCanvasListener
        implements MouseMotionListener
{

    private static final Logger logger = Logger.getLogger( CanvasMouseMotionListener.class.getName( ) );

    /** Number of pixels that must be moved before a goto is enabled. */
    private static final int DRAG_THRESHOLD = 16;

    /**
     * Temporary variable for checking if we need to recalculate the
     * path when dragging units.
     */
    private Tile lastTile;


    /**
     * Creates a new listener for mouse movement.
     *
     * @param freeColClient The <code>FreeColClient</code> for the game.
     */
    public CanvasMouseMotionListener( FreeColClient freeColClient, Canvas canvas )
    {
        super( freeColClient, canvas );
    }


    /**
     * Invoked when the mouse has been moved.
     *
     * @param e The MouseEvent that holds all the information.
     */
    @Override
    public void mouseMoved( MouseEvent e )
    {
        if ( e.getY( ) >= AUTO_SCROLL_SPACE )
        {
            performAutoScrollIfActive( e );
        }

        if ( canvas.isGotoStarted( ) )
        {
            if ( canvas.getActiveUnit( ) == null )
            {
                canvas.stopGoto( );
            }

            Tile tile = canvas.convertToMapTile( e.getX( ), e.getY( ) );

            if ( tile != null )
            {
                if ( lastTile != tile )
                {
                    Unit active = canvas.getActiveUnit( );
                    lastTile = tile;
                    if ( active != null && active.getTile( ) != tile )
                    {
                        PathNode dragPath = active.findPath( tile );
                        canvas.setGotoPath( dragPath );
                    }
                    else
                    {
                        canvas.setGotoPath( null );
                    }
                }
            }
        }
    }

    /**
     * Invoked when the mouse has been dragged.
     *
     * @param e The MouseEvent that holds all the information.
     */
    @Override
    public void mouseDragged( MouseEvent e )
    {

        performDragScrollIfActive( e );

        Tile tile = canvas.convertToMapTile( e.getX( ), e.getY( ) );
        if ( tile != null
                && ( ( e.getModifiers( ) & MouseEvent.BUTTON1_MASK )
                == MouseEvent.BUTTON1_MASK ) )
        {
            // only perform the goto for the left mouse button
            if ( canvas.isGotoStarted( ) )
            {
                Unit active = canvas.getActiveUnit( );
                if ( active == null )
                {
                    canvas.stopGoto( );
                }
                else if ( lastTile != tile )
                {
                    lastTile = tile;
                    PathNode dragPath = active.findPath( tile );
                    canvas.setGotoPath( dragPath );
                }
            }
            else
            {
                // Only start a goto if the drag is 16 pixels or more
                Point dragPoint = canvas.getDragPoint( );
                int deltaX = Math.abs( e.getX( ) - dragPoint.x );
                int deltaY = Math.abs( e.getY( ) - dragPoint.y );
                if ( deltaX >= DRAG_THRESHOLD || deltaY >= DRAG_THRESHOLD )
                {
                    canvas.startGoto( );
                }
            }
        }
    }
}
